Flashcards in Chapter 5 (152-157, 174-183) Test 2 Deck (31):
What is the size of a ethernet message field?
-Ethernet has max packet size of 1492
-need to subtract size of the TCP header(24 bytes)
-subtract size of IPv4 header(24 bytes
-therefore the max packet size is 1444
Describe the transport layer.
-links the application layer software in the application layer with the network
-segments large messages into smaller ones for transmission
-manages the session(end-to-end delivery of message.
What does NAT do?
-network address translation
-translates private non-routable addresses to a routable IPv4 address.
What are the three major functions performed by the transport layer?
-linkin the application layer to the network layer
Describe port addresses.
-each application layer software package has a unique port address.
-applications must tell TCP the application layer port address that is to receive the message.
-sending computer tells TCP the source and destination port address.
What fields are the port addressed placed in the TCP segment?
-the first two fields.
How many bits are port addresses?
What are common well known ports?
http: port 80
FTP: port 21
Telnet: port 23
SMTP: port 25
-takes one outgoing message from the application layer and break it into a set of smaller segments for transmission through the network.
-also means to take incoming set of smaller segments from the network layer and reassemble them into one message for the application layer.
Describe how TCP ensures all segments are received?
-Continues ARQ(chapter 4).
What is the default segment size for transport layer?
-Transport layer at the sender negotiates with the transport layer at the receiver to settle on the best segment sizes to use.
-done by establishing a TCP connection between the sender and receiver.
Describe a session.
-conversation between two computers.
What are the two types of messaging?
Describe connection-oriented messaging
-sets up a TCP connection(session) between sender and receiver.
Describe the three way hand shake.
-sender sends a SYN segment.
-server responds with an ACK and sends its own SYN
-client seands an ACK for server's SYN
Describe a SYN.
-usually a randomly generated number that identifies a packet.
What does TCP use to ensure arrival of segments?
-continuous ARQ (sliding window).
Describe the TCP four-way handshake.
-sender willl send FIN to inform the receiver that it is finished sending data
-server acknowledges with an ACK
-server then sends a FIN
-Sender sends an ACK.
Describe conectionless messaging.
-each packet is treated separately and makes its own way through the network.
-no connection is established.
-sender sends packets as separate unrelated entitites.
-may arrive out of sequence so network layer will put sequence number on each packet..
How big is the UDP packet?
When is connectionless messaging used?
-when application data or message can fit into one single message.
Give examples of application layer software that uses TCP?
-HTTP, SMTP, FTP, Telnet.
What applications use UDP?
-DHCP, routing control messages(RIP), network management(SNMP).
-quality of service.
-connection oriented messaging in which different connections are assigned different priorities.
-different classes of service are defined with different priorities.
What happens when transport layer software attempts to establish a connection?
-specifies the class of service that the connection requires.
-when a connection is established, network ensures that no connections are established that exceed the maximum number of that class on a given circuit.
Describe Resource Reservation Protocol(RSVP) and Real-Time Streaming Protocol(RTSP).
-permit application layer software to request connections that have certain minimum data transfer capabilities.
-used to create a connection and request a certain minimum guaranteed data rate.
-use Real-Time Transport Protocol(RTP) to send packets across the connection.
What does RTP contain?
-info about sending app
-packet sequence number
-time stamp so that the data in the RTP packet can be synchronized with other RP packets.
Does RTP replace TCP or UDP?
-no, combined with UDP.
-each relat time packet first created with RTP and then surrounded by a UDP datagram.
What does a router do when it receives a frame?
-peforms error checking and sends an acknowledgement.
What transport layer protocol does DNS use?